A Revision of the 1783?1784 Calabrian (Southern Italy) Tsunamis L
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A revision of the 1783?1784 Calabrian (southern Italy) tsunamis L. Graziani, A. Maramai, S. Tinti To cite this version: L. Graziani, A. Maramai, S. Tinti. A revision of the 1783?1784 Calabrian (southern Italy) tsunamis. Natural Hazards and Earth System Sciences, Copernicus Publ. / European Geosciences Union, 2006, 6 (6), pp.1053-1060. hal-00299395 HAL Id: hal-00299395 https://hal.archives-ouvertes.fr/hal-00299395 Submitted on 13 Dec 2006 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Nat. Hazards Earth Syst. Sci., 6, 1053–1060, 2006 www.nat-hazards-earth-syst-sci.net/6/1053/2006/ Natural Hazards © Author(s) 2006. This work is licensed and Earth under a Creative Commons License. System Sciences A revision of the 1783–1784 Calabrian (southern Italy) tsunamis L. Graziani1, A. Maramai1, and S. Tinti2 1Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma 2, Rome, Italy 2University of Bologna, Dipartimento di Fisica, Settore Geofisica, Bologna, Italy Received: 28 September 2006 – Revised: 23 November 2006 – Accepted: 23 November 2006 – Published: 13 December 2006 Abstract. Southern Italy is one of the most tsunamigenic 1 Introduction areas in the Mediterranean basin, having experienced during centuries a large number of tsunamis, some of which very In the Mediterranean basin, Italy is one of the countries most destructive. In particular, the most exposed zone here is the affected by tsunamis. During centuries it has experienced a Messina Straits separating the coasts of Calabria and Sicily large number of events, some of which caused catastrophic that was the theatre of the strongest Italian events. In 1783– effects, severe damage and thousands of victims. The analy- 1785 Calabria was shaken by the most violent and persis- sis of the Italian Tsunami Catalogue (ITC, Tinti et al., 2004) tent seismic crisis occurred in the last 2000 years. Five very shows that southern Calabria, Messina Straits and eastern strong earthquakes, followed by tsunamis, occurred in a short Sicily are certainly the most active tsunamigenic regions in interval of time (February–March 1783), causing destruction Italy. As a matter of fact, the majority of the Italian tsunamis, and a lot of victims in a vast region embracing the whole including the strongest ones, occurred here: most were the southern Calabria and the Messina area, Sicily. In this study results of coastal and submarine earthquakes, but some were we re-examined these events by taking into account all avail- also due to volcanic activity and submarine slides. able historical sources. In particular, we focussed on the 5 The geological setting of the area is quite complex and and 6 February 1783 tsunamis, that were the most destruc- some aspects are still poorly understood. Structural anal- tive. As regards the 5 February event, we found that it was ysis and seismological and deformation (VLBI and GPS) underestimated and erroneously considered a minor event. data show a regional extensional ESE-WNW trend which is On the contrary, the analysis of the sources revealed that in coupled with a strong 1.5–2 mm/yr uplift of the whole Cal- some localities the tsunami effects were quite strong. The 6 abrian arc region (Monaco et al., 1996; Tortorici et al., 2003; February tsunami, the strongest one of the sequence, was due D’Agostino and Selvaggi, 2004; Jenny et al., 2006). One of to a huge earthquake-induced rockfall and killed more than the main tectonic features is the belt of normal faults running 1500 people in the Calabrian village of Scilla. For this event for more than 350 km along the Apennines chain and extend- the inundated area and the runup values distribution were es- ing from Calabria to Sicily, which is formed by distinct fault timated. segments with maximum length of about 40–50 km that are Further, the analysis of the historical sources allowed us responsible for the major earthquakes. Some of the faults are to find three new tsunamis that passed previously unnoticed found close to the coast or are completely placed offshore and that occurred during this seismic period. The first one with great potential for tsunami generation. The most ener- occurred a few hours before the large earthquake of 5 Febru- getic historical shocks reached the maximum magnitude of ary 1783. The second was generated by a rockfall on 24 M∼7 (Boschi et al., 2000) and almost all were accompanied March 1783. Finally, the third occurred on 9 January 1784, by sizable tsunamis. probably due to a submarine earthquake. Before focusing on the 1783–1785 seismic period, it is worth mentioning the two largest tsunamigenic earthquakes that occurred in Calabria and Sicily, namely the 1693 east- ern Sicily and the December 1908 Messina Straits events (Fig. 1). Correspondence to: A. Maramai At the beginning of 1693 a tremendous seismic crisis hit ([email protected]) eastern Sicily, culminating in the main shock of 11 January Published by Copernicus GmbH on behalf of the European Geosciences Union. 1054 L. Graziani et al.: Revision of the 1783 Calabrian tsunamis 39.200 N sequence was exceptionally long and destructive, the associ- 14.300 E CALABRIA ated tsunamis were almost disregarded as secondary minor N TYRRHENIAN events, except for the 6 February Scilla tsunami that caused SEA much more casualties than the parent earthquake itself. This unusual and long seismic period stirred up great interest in many Italian and foreign scientists and scholars, that went on the field to make direct observations and to document the effects. As a result, a vast amount of reports, chronicles, 1908 works and maps representing the devastation was produced Messina Scilla and this constitutes today a precious source of information Reggio Calabria for studying the earthquake effects and consequences, in- Pellaro IONIAN cluding tsunamis. By carrying out a deep analysis of the S. Alessio SEA available sources it was possible to count as many as ten dis- Giardini Naxos tinct tsunami events, most of low intensity, three of which SICILY were never mentioned before in the modern scientific litera- Catania ture. For the largest tsunamis, the available data allowed us to draw a rather reliable picture of the effects and, in particu- 1693 Augusta lar, for the 6 February Scilla event it was possible to perform the reconstruction of the inundated area and to determine the Siracusa distribution of the run-up values. This work contributes to the updating of the ITC (Tinti et Noto 36.800 N 17.400 E al., 2004) and, for this purpose, the events studied here were classified according to the evaluation standards adopted for Fig. 1. Epicentres of the earthquakes generating the most destruc- the catalogue compilation. tive tsunamis in southern Calabria and eastern Sicily. Localities most affected by waves are reported. 2 The 1783–1785 Calabrian seismic sequence with estimated magnitude M=7.4 (CPTI2, 2004). It pro- In 1783–1785 the southern part of Calabria was struck by duced almost complete destruction within an area of about one of the most impressive and persistent seismic crisis that 2 14 000 km extending from Catania to Noto and Siracusa, occurred in the last 2000 years. A lot of sources are avail- causing more than 54 000 casualties (Boschi et al., 2000). able in the literature: many famous coeval writers and a A tsunami was observed along the whole eastern Sicily coast lot of current historiographer studied and documented this with major effects at Augusta and Catania. First the sea with- seismic period. During our study we examined more than drew from the shoreline and the following inundation was 100 bibliographical sources, the most reliable ones, and we very damaging and lethal for many people. At Augusta, the also performed extensive research in many public and private water waves were likely as high as 15 m (Tinti et al., 2004). archives, libraries, etc., in order to collect new data. The cri- The 28 December 1908 Messina earthquake is one of sis lasted more than three years, starting at the beginning of the strongest earthquakes that ever occurred in Italy. The February 1783 and, during a period of about two months five towns of Messina and Reggio Calabria together with many large earthquakes (with epicentral intensity MCS≥IX) oc- other villages were completely destroyed. Partial destruc- curred along a zone about 100 km long, devastating southern tion involved most of Calabria and Sicily over an area about Calabria between Reggio Calabria and Catanzaro. The first 6000 km2 wide. More than 60 000 people died. A violent destructive earthquake of the sequence ocurred on 5 Febru- tsunami followed the shock, causing severe damage and hun- ary 1783, and was followed by the other main shocks re- dreds of victims in the Messina Straits zone. In most places spectively on 6 and 7 February, and on 1 and 28 March in the sea first receded for a few minutes from the usual level the same year. All these earthquakes resulted to be tsunami- and then flooded the coast with at least three big waves. The genic, though the size of the generated tsunamis differed very sea level oscillations lasted for many hours. The tsunami much from case to case. The epicentres of the five main reached its maximum intensity in the Calabrian coast near shocks migrated northward from the Aspromonte area to the Pellaro, where run-up heights as large as 13 m were observed, Sant’Eufemia and the Squillace gulfs (Fig.